Using a transceiver to emit microwave and to detect the signal reflected by a measured object is a commonly used detection method. In the object detection technology of the prior art, the I/Q signal can be directly converted to extract phase information. However, in the signal processing, DC offset, flicker noise, and leakage from the transmitter to the receiver cannot be easily reduced. For this reason, solutions are still needed to improve the shortcomings of the prior art.